


but you're not fooling me, cause i can see the way you shake&shiver

by melbopo



Category: Shadowhunters (TV), The Shadowhunter Chronicles - All Media Types
Genre: All other characters are SUPER minor, Alternate Universe - Human, Fluffy Ending, Halloween Costumes, Kissing, M/M, Mutual Pining, Neck Kissing, The background relationships are Malec and Clizzy, The main characters of this fic are the people in the relationship, There is background past Clace, Tooth-Rotting Fluff, because I just want everyone to be not be straight and fall in love tbh, but seriously, jimon, once again I wrote an extremely fluffy fic, they are so minor that you should not read this unless you are in it for
Language: English
Status: Completed
Published: 2016-10-31
Updated: 2016-10-31
Packaged: 2018-08-28 05:18:37
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,434
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8433280
Author URL: https://archiveofourown.org/users/melbopo/pseuds/melbopo
Summary: Finding a cool costume for Jace's Halloween party is totally something within Simon's capability. It shouldn't be that hard, right? He definitely has something he can pull together last minute and on the day of the party. Wait, does Jace mean like Simon-cool or Jace-cool? That's a stupid question. Obviously he means Jace-cool. Shit. Looks like Simon won't be reusing his Spiderman cosplay from last year...tl;dr: a slight costume fueled panic, a little misunderstanding, some feelings, and lots of fluff!------This fic was written for the  Jimon Halloween Fic Event! TY For the inspiration!





	

**Author's Note:**

> The BIGGEST of thank yous to my love [Emily](http://castiel-grant-stilinski.tumblr.com/) for being my FIRST beta ever!!! She is a complete gift and I definitely wouldn't have finished it if it wasn't for her - so thank you a million times over! All remaining mistakes are mine that I edited last minute without her careful eye...
> 
> Also, the title of the fic comes from the Scooby Doo Where Are You theme song cause scooby doo is my weakness.
> 
> Happy Halloween my ghosts, ghouls, and nb boos!!! Enjoy!

[ ](http://www.mel-iorn.tumblr.com)

Simon is little proud of himself for waiting a full minute after hanging up his phone call with Jace before panicking and calling Clary. It has to be a relatively new record for him, especially when Jace is involved. Simon is the first to admit, especially to himself, that there is just  _ something _ about Jace that makes Simon a little more nervous and a little more on edge. It might have to do with his piercing eyes that feel like they are always seeing straight into Simon’s very soul or the tiny upticks in Jace’s lips when Simon really gets going on a particular topic or maybe it is directly related to the way Jace’s shirts seem extra tight these days- okay, maybe he should stop that dangerous train of thought! Maybe the answer is there is no singular answer and this list is making Simon panic even more because maybe there is something he needs to acknowledge himself? Maybe he should just keep ignoring it though because it’s worked well for him for the past year or so and what is a little self denial? It only messes with your self esteem a little and makes every single interaction open to intense scrutiny for decoding hidden meanings. Right?! Why hasn’t Clary picked up yet? Simon  _ needs  _ her rationality right  _ now _ . 

Simon hangs up the current phone call and tries again, as he begins pacing back and forth on the rug in his bedroom. This time she picks up on the fourth ring, her voice a little breathless as she asks, “Simon? Are you okay? What happened?”

And honestly, that is all the prompting Simon needs at this point because he is so keyed up. The words stream out of his mouth, a little fast and a little mumbled, “he told me to wear something cool Clary! Something cool! What does that even mean? Like does he mean me-cool or him-cool? Well, obviously he means him-cool cause he doesn’t think anything about me is cool and I don’t want him to kick me out of the party but what does he even think is cool. I mean I know he is into the bad bo-”

“Simon. Simon. Simon!” It takes Clary calling his name taking a couple of tries to breakthrough his verbal stream of conscience. He pauses to take in a breathe. “Pause. Rewind to the beginning. I need more context clues. Who and what are you talking about?”

Simon throws his free hand up in the hair in exasperation, even though Clary can’t see him, as if the answer is obvious. “Jace, of course! He said I need to wear a cool costume to his party tonight! Wait, he’s your ex, what do you think he means by cool?”

The annoyed huff Simon hears in response is a tell tale sign that Clary is definitely rolling her eyes at him right now. “Simon, how many times do I have to remind you that Jace has been my ex for many years now and you really should stop referring to him as my ex. Wait, why are you so nervous about this? Do you want to impress him?”

“What?! No! That’s- that’d be crazy. And I’m not nervous!” There is a button click before Clary’s voice coming from Simon’s phone is little noisier, “you were doing your trademarked nervous ramble. We’ve been best friends for over two decades, I can pick up on these things.”

Simon opens  and closes his mouth a couple of times in disbelief as his mind sputters to come up with the perfectly sound reasoning he mentioned earlier. “No, I just don’t want Jace to bar me from entering the party because my costume isn’t up to his standards of cool.” An unconvinced  “hmmm” and a definitely non-Clary-woman’s laugh are the responses he gets. He squacks in disbelief, “Am I on speakerphone again??”

Clary’s voice sounds a little annoyed as she says, “you interrupted  _ our  _ moment, Simon.” The woman laughs again in the background. ”Don’t stress about the costume, Izzy has something you can wear.” Izzy chimes in, “Yeah I got something from Jace that’ll be perfect. I’ll drop it off in an hour… or two.” Clary giggles this time and Simon rolls his eyes saying “thank you” before ending the call.

~~~~~~

It has been about two hours since Simon’s phone call with Clary and he is starting to get  anxious because Izzy still hasn’t shown up with the promised costume and the party is in about an hour which really doesn’t give him a lot of time to get ready. What if the costume doesn’t fit him or requires some sort of get up? He’s debating if he would be broadcasting his nerves loud and clear if he were to just call Izzy for a check in when his phone on his desk with a new message. Simon only trips a little bit over his own feet in his haste to check and see if it’s from Izzy. He makes a noise of triumph when he sees her name on his lock screen. Her text says she couldn’t stop in because her costume was way more time consuming than she imagined and yeah and yeah but she dropped the costume off on his porch - score! 

Simon brings in the rather heavy bag, barely holding in his excitement until he is safely in his bedroom. He puts the bag on his bed to open it up and to go through it. He sees Izzy’s hand written note of encouragement first, ‘ _ enjoy nerd  _ _ ❤︎ _ ’, in her fast partial cursive scrawl. He grins a little at the affectionate nickname before he pulls out thick black fabric from inside of the bag. He unfolds it to reveal the official Universal Studio Gryffindor robes and a matching skinny maroon tie. Obviously his mind jumps to being Harry Potter because honestly? He is already 70% there if he wears a white button down and black jeans with his messy hair and glasses, the robes definitely push him that additional 30% to bring his costume to the next level. But shit… that’s almost too easy. Jace would definitely find the costume to be not cool enough for the party (aka way too nerdy). Maybe he can still use all the pieces but just rearrange them a little… and he is pretty sure he has fake vampire teeth prize in his drawer from that time him and Jace went to the arcade over the summer. And vampires are definitely cool, that’s what makes them such a classic Halloween costume, right?

~~~~~~

Simon is preening only a little bit at the fact that he is able to get his whole costume together, make up done, hair styled, and only be thirty minutes late to the party. He had to drive to three different Party and Halloween Stores to find one that had fake blood face paint in stock. He only needed a little but it was crucial for his whole costume and general aesthetic.

The door to Jace’s apartment is already open a crack, so Simon lets himself in. He follows the sound of the Scooby Doo theme song down the hall to the living room where fake cobwebs and purple twinkle lights are hanging as decorations. The decorations actually look really cool, like Jace and Alec put a decent amount of time into getting their apartment festive for the party. He even spies a pumpkin with a pitcher spout on the snacks table and he grins on reflex at the fact that Jace listened to his suggestion.

He glances around for the familiar faces of his friend group. He can see Alec dressed as Alexander the Great with his arm around Magnus in his elegant Hephaestion costume - which is just classic for them. He can see Izzy, Clary and someone’s cloaked back in the other corner of the room. Izzy is in a  [ spot on Harley Quinn costume ](http://ampcosplay.tumblr.com/post/147979077128/model-soni-aralynn-photog-ampcosplay) , whispering something in Clary’s ear, who is wearing from what he can see around the stranger, a homemade  [ Poison Ivy costume  ](https://www.flickr.com/photos/thealiveproject/15261791061/in/album-72157647687089132/) which would make for a perfect couple’s costume since Izzy’s current favorite comic series is DC’s Bombshells. The idea is kinda sickly cute even for them but-wait, is everyone in a couples costumes except for him?! He didn’t know this was a couples costumes kind of event and if he did, he would have at least tried to plan something. Maybe convince Jace to do a matching couple’s costume with him. Couple of besties of course…Best friends, erm bros, do that, right?

The cloaked stranger turns around quickly and Simon realizes it’s Jace, a smile on his face as he extends his arm towards Simon, “Simon! You finally made it. I was starting to get worried that we might have to send out the mystery gang to find you.” 

Simon walks towards the three of them, rolling his eyes at Jace’s teasing comments. He hears Izzy say, “I gotta see this” which confuses him a little-see what exactly? His costume in full deadly, glory? Clary grabs Izzy’s hand and leads her away with a response of, “not from this close babe- let’s go get some Fangria from the Pumpkitcher,” which makes him squint his eyebrows even more in confusion. Oh they must mean see the fact that he is clearly failed the party’s cool couples costumes protocol.

Which is definitely 100% Jace’s fault for not telling him ahead of time about the party plan. Once he is close enough he hits Jace’s bicep with the back of his hand, trying not to let the fact that it definitely hurt his fingers more than it did to Jace, who doesn’t even flinch at the hit, just looks perplexed. “Jace! You told me cool! Not to find a date!”

Jace’s confused face leaves Simon’s as he takes in Simon’s costume: he is wearing the maroon tie with a white long sleeve button up, black skinny jeans, the Gryffindor robes reversed so the patch and hood are inside with the maroon on the outside. He even put greyish powder on his face with fake blood dripping down from his lip to make him look extra undead in case his fake teeth didn’t clue people in on his costume.

Simon tries not to fidget on Jace’s slow trailing gaze, feeling literally undressed and incredibly judged in the moment. When Jace’s eyes finally return to his face, Simon makes sure to flash a smile to accent the elongated canine fake teeth he decided to buy since the plastic vampire teeth would be be uncomfortable all night. And Simon is nothing but dedicated to the costume etiquette - he cosplays and believes that once in costume, he needs to stay in it for the whole event.  Jace’s voice sounds uncertain as he ask, “You’re a vampire?”

Simon uses both of his hands to gesture to his whole body in an ‘obviously’ gesture, “Yes! You told me cool!”

Jace’s eyebrows scrunch to mirror the confusion that can be heard in his voice, “But I even gave you robes and a tie…” And now it’s Simon’s turn to be perplexed. He actually takes the moment to look at Jace’s costume more clearly, beyond the fact that he is wearing a black cloak-wait no that is a robe too! Wait, it’s a Slytherin robe? Simon can see the dark green trim and Slytherin patch on the chest. A matching dark green tie is loosely tied around Jace’s neck over his white long sleeve button up like he had been fiddling with it and loosened it. As the silence ticks on, Jace’s face becomes paler and paler before he mutters, “shit. Shit. Did I read this whole dynamic wrong? Man, I’m sorry-”

Simon’s eyes flick back up to Jace’s pale face at the sound of an apology, his mind going a mile a minute to try and put all the pieces together. Looking into Jace’s eyes, he can fully take into the fact that Jace’s blonde hair is perfectly slicked back like a certain troubled Slytherin character that Simon definitely has a soft spot for. Admittedly, it is a little embarrassing for how long it takes for all the bits to slip into place. He bursts out in shock in the middle of Jace’s weird apology of sorts, “Wait! You dressed up as Draco Malfoy for me?”

Jace’s cheeks turn red as he looks down at the ground between them, breaking eye contact as he shrugs before looking back up at Simon from under his lashes (wait, have Jace’s eyelashes always been that long and pretty?) in an almost bashful manner. “Yeah... I even got you those stupid wizarding robes you’ve been talking about non stop since we marathoned Harry Potter over the summer.”

Simon still isn’t 100% sure that this isn’t some weird prank or that Jace lowkey tried to plan their bro couple costume and he messed it up or something else entirely. Even the vague promise of that something else makes Simon’s insides flutter and feel hopeful that he isn’t alone in feeling like there has been something different and new and maybe even a little scary between  _ them _ . He isn’t positive though, so he tries to give Jace one last out before this becomes something that he isn’t sure he can just laugh off. He shrugs nonchalantly back as he clarifies, “well I was going to go as Harry butttt….” He draws out the word until Jace gives him a little half smile, “you said to dress cool so…”

Jace’s smile grows to be full fledged as he rolls his eyes. “Harry Potter’s cool cause you’re into it. I mean you made me watch all eight movies and I don’t even like Harry Potter..." Simon won’t lie, he got a little distracted while Jace was talking because this grin is one of his top ten things in life that always makes that weird feeling happen in his stomach, especially when he knows that he’is the reason it’s made an appearance on Jace’s face. Which means Simon’s watching Jace’s lips move cause how could he not when they are so pink and soft looking and wait - Simon’s eyes jump back to Jace’s as he exclaims, a little outraged on behalf of his favorite book and movie series. “What do you mean you don’t like Harry Potter! You’ve seen all eight movies!” 

Jace blushes a little darker and does his casual shrug again, which is starting to look like a deflection technique to Simon... “Maybe I didn’t watch them for their content…” Simon can’t help the face of confusion at that comment because who doesn’t like adventure, magic, and love?? “...but for the company…”

That’s what really solidifies this moment for Simon, that hopeful feeling growing in his stomach, at the thought of that other possibility, is past the the point of no return for him. He can’t keep the disbelief and hopefulness out of  his voice as he asks, “you watched them to just spend time with me?”

Simon’s eyes are watching Jace’s with an intense gaze, looking for any sort of clue as to what exactly Jace is getting at. Jace’s cheeks are bright red as he mumbles, “I really like when you get excited about nerdy stuff. I seeing you get passionate about something - I think… I think it’s really attractive. Your cheeks get red and your eyes shine and you get the biggest smile on your stupid, beautiful mouth-” Simon puts a hand up, his mind spinning in complete disbelief that they are going here right now and that Jace definitely feels that  _ something  _ between them too.

”Hold on… I think I’m dreaming… or something. How else would that explain the fact that Jace Lightwood just complimented me?” Simon asks, partially in disbelief, partially teasing Jace with a happy smile on his lips. 

Jace’s whole body relaxes the moment Simon smiles He pulls Simon closer with his hand on the maroon tie, his eyes fond before becoming cross eyed at the proximity, “Do you wanna wake up or can I kiss you?”

Simon whispers in the heated hair between their lips, excitement running up his spine at him finally acknowledging this electricity between them. “You should definitely kiss me. Wait, if I wake up, would that make you my prince charm-”

Jace kisses him mid question with a big, full teeth smile on his face that causes their first kiss to be a little awkward and uncomfortable because Simon can’t stop smiling too (Jace kinda has that effect on him). Then the reality hits of the fact that they are kissing; Jace’s lips are finally on his and Simon just kinda melts into it. He's ignoring the catcalls and whistles from around them, as he trades soft kisses with Jace, just starting to learn his mouth and thinking about how he could do this for hours - map Jace’s lips, his mouth, his everything with his lips. Which reminds him of something very important and he pulls away suddenly. He definitely preens and smirks at the fact that Jace’s lips follow after his, even with his eyes closed. “Wait does this mean you like me like me? Are we dating now?”

Jace bites his already red and shiny (from Simon-from  _ their _ kisses) bottom lip, looking nervous as he says “yeah I like like you and I’d like to date if… you know, you’d like to date?”

“Fuck yes”, Simon mutters as he puts one hand on the back of Jace’s head and the other on Jace’s hip to pull him into a deeper kiss, that makes his knees a little weak cause Jace just parts his lips for Simon and damn that is way hotter than he ever could have imagined. He nips at Jace’s bottom lip which causes Jace to separate from the kiss fast, confusion written all over his face as he looks at Simon’s mouth. He must realize something because his face relaxes and his cheeks become a little red again. “Oh… feel free to keep kissing me with those on…” 

Simon squints at first, running his tongue over his lips to chase the taste of Jace’s kiss. He watches Jace’s eyes dilate at they track his tongue-oh, the motion causes his tongue to run into his fake canine teeth that he forgot he’s still wearing. His face goes serious as he says in the worst Dracula expression possible, “I’m going to suck yer blooddd!” going for Jace’s neck, right above the collar of his white button up. Jace just laughs as he mutters in the fondest voice that Simon has ever heard in regards to himself, “what a nerd-” but startled groan escapes Jace’s lips when Simon’s actually makes contact with his neck. Jace mutters a soft “shit” as his hand grabs Simon’s hip to keep him close (which definitely boosts Simon’s ego).

Jace’s voice is breathy and a little strangled as he says, “screw this party - let’s go make out in my room.” Simon stops nibbling a pretty sizeable mark on his  _ boyfriend _ ’s neck to raise an eyebrow at him, “but you and Alec planned this whole Halloween party.” Jace smiles as he releases Simon’s tie to rest his palm against Simon’s jaw, his thumb gently stroking Simon’s cheek. He looks vulnerable in a way that Simon’s never seen him before, especially not from this close. “I threw this whole party for you cause I know how much you like dressing up for Halloween. I just wanted to have an excuse to dress up with you.”

Simon’s heart straight up melts at Jace’s admission, his mind wondering how many other things Jace did just so they had an excuse to hang out more together. It makes him feel better about this, about them, because he knows for the past year or so, he’s been doing same thing-always looking for events or moments to spend with Jace. He finally allows that warm, hopeful, fluttering feeling in his stomach to consume him as he leans forward to recapture Jace’s lips in his for a quick kiss before muttering his own personal confession, “I’m kinda crazy about you.”

Jace’s blinding smile in response is worth every moment of Simon’s vulnerability, “I’m crazy about you too… I’ve just been in denial about it for a while now.” Simon can hear Alec yell, “Gross!” in the background and he feels Jace’s hand leave his hip to no doubt flip Alec off. But not even Alec or their audience can ruin this moment for him. Simon responds with confidence, “think I’ve been too.”

**Author's Note:**

> If you enjoyed this fic, you will also probably love this [similarly Halloween Themed Jimon fic by my dear, Lilly!](http://archiveofourown.org/works/8257996)
> 
> what? another fluffy fic from me?? I HAVE NO APOLOGIES!!! I just want nice things for my Shadowhunter bbis! Did you like my characterization of Simon? I think we are kinda similar so I tried to write him with a kinda rambly and excited narrative but I could have totally missed the mark... I will write more than just a one shot one of these days I swear!
> 
> Liked the fic? Wanna talk Malec, Clizzy, Allydia, and/or the fact that Luke Garroway is a main character with me?? Check out my tumblr, [@melbopo](http://www.melbopo.tumblr.com)!


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